Deer Diseases: Are You At Risk?

Whitetails do carry a number of parasites and diseases, but which ones are worth worrying about?

Hunters have every reason to be concerned about contracting some strange disease from the deer we harvest. Not only are we handling animals that aren’t subject to any federal health guidelines, but we regularly and willingly stick our hands in guts that are likely to be tainted with some form of parasite or disease.

Veterinarians at Oklahoma State University identified 28 internal and external parasites on whitetails in Oklahoma alone. Ticks are easy to identify, but most parasites are invisible to the human eye. Some, like nematodes, are small worms that are not only visible but downright creepy. They can measure up to three inches long and they live on or in various internal organs. So should we worry? They might turn your stomach, but none pose any threat to humans, says Dr. Mike Dunbar, a wildlife research biologist with the U.S. Department of Agriculture’s National Wildlife Research Center in Colorado.

“It’s not out of the question to get Lyme disease from a tick that fell off a deer and attached itself to you, but the risk is no greater than getting it from a tick that came from your garden,” says Dunbar.

Chronic wasting disease (CWD) is perhaps the most publicized malady to make headlines in recent years. Virtually every state wildlife agency has some sort of testing program in place, and they’ve done a good job of keeping the hunting and non-hunting public informed. Still, plenty of hunters are taking a second look at the packages of venison in their freezer and wondering if it is safe to eat. A lot is unknown about CWD, but scientists have said that there is no evidence that the disease is transmittable to humans. However, Dunbar, who specializes in wildlife diseases, says no one knows for certain.

“There are no confirmed cases of anyone becoming infected with CWD,” he says.

Lesser-Known Concerns

A variety of other diseases either don’t make headlines at all or only rank as a footnote in the outdoors column of a local newspaper, and generally they are of little concern to deer hunters. Epizootic hemorrhagic disease, or EHD, is a virus spread by biting midges, tiny flies that serve as the disease’s host. EHD is prevalent in the South and Southeast and has responsible for large-scale deer die-offs at times. It’s also been detected in whitetails in Wisconsin, Ohio and Pennsylvania, but it has a much greater impact on deer herds in warmer climates. Kentucky and Tennessee experienced a major outbreak in the summer of 2007 and parts of Virginia saw a massive die-off of whitetails in 2002. The disease is most prevalent in hot, dry conditions when deer gather around limited water sources. Infected animals become weak and disoriented, and they often bleed from the mouth and anus. The outer sheaths on their hooves fall off as well, and their tongues sometimes turn blue. It’s an unforgettable sight and one that might make a hunter think twice about eating another bite of venison. Like most other whitetail diseases, however, EHD has no effect on humans. Some deer even survive it and ultimately build an immunity to it.

One disease that can transfer to humans is bovine tuberculosis. Biologists discovered bovine TB in deer in Michigan’s Lower Peninsula in 1975. Since then, nearly 140,000 whitetails have been tested, and more than 500 have tested positive. It’s a tiny fraction, but Michigan Department of Natural Resources personnel, along with scientists from the U.S. Department of Agriculture’s Wildlife Services division, have determined that 30 percent of coyotes in that same region are also infected with bovine TB. The risk to humans is extremely low, notes Dunbar, but a hunter in Michigan did develop tuberculosis from field-dressing an infected whitetail. Thankfully, the hunter recovered.

“The biggest threat of bovine TB is to cattle. When it infects cows, the entire herd has to be destroyed, so it can have a devastating effect on local economies if it spreads through the cattle,” Dunbar says.

Other potential diseases include contamination from E. coli, a bacteria that is harbored in feces. Dunbar doesn’t know exactly how frequently hunters become sick from E. coli, but he does know that it has happened on several occasions. Sampling of hunter-killed deer in Georgia in 1998 found a very low rate of E. coli. Only three animals out of 400 were contaminated, and subsequent testing of the meat from those infected deer came back negative.

How To Protect Yourself

Not sure if your deer is safe to eat? The obvious solution, of course, is to cook venison thoroughly. According to the Partnership for Food Safety Education, steaks and roasts should be cooked to an internal temperature of 145 degrees, while ground meat should be cooked to at least 160 degrees. However, the proteins that make up CWD aren’t destroyed through cooking. Therefore, health experts warn hunters not to eat meat from animals that appear sick or otherwise abnormal from areas known to harbor the disease. It’s also a good idea to follow some basic precautions in known CWD areas, says Dunbar: “Because the prions are in neurological tissue, it’s recommended that hunters bone out their game and discard the brain and spinal tissue.”

To avoid the possible risk of infection from any disease, avoid shooting any deer that doesn’t look or act normal. If you do see a deer that doesn’t look normal, notify the local game department office. Biologists will certainly want to know about it. Wear gloves when field-dressing the deer, especially if you have cuts or scratches on your hands and forearms. Also, prevent urine and feces from touching meat and avoid cutting through spinal columns. Above all, however, don’t worry about picking up a disease from the deer you just killed. The risks involved with driving to and from your favorite deer woods far outweigh any risk associated with gutting a buck.

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